Sash windows which open top and bottom: do they work? Better air circulation? (Victorian air conditioning)

[ParentOfOne]

Does anyone have the kind of sash windows which open both from the top and the bottom? Ie where you can, at the same time, leave a gap both at the top and the bottom?

I'm talking about those like https://uniquewindowservices.com/wp-content/uploads/2018/10/Sash-Balances-Graphic.png
or https://www.lomaxwood.co.uk/news/sash-windows-are-a-energy-efficient-air-conditioner-we-all-need-this-summer/
or https://www.dailymail.co.uk/news/article-12182865/Enjoy-Victorian-air-conditioning-Homeowners-sash-windows-use-homes-cool.html

The theory is that this allows better air circulation, because hot air flows at the top and cooler air at the bottom. Some call it "Victorian air conditioning" :)

That's the theory, but does anyone have it and what have they experienced in practice?

Before people tell me the UK doesn't have Spanish weather, the point is not how often it is 30C outside, but how often it is, say, 24C outside and 30C inside. With many properties in the South of England, especially for south facing rooms, the answer is: quite often. Plus, regardless of temperature, it is nice to have some air circulation, even in the winter (but of course for shorter periods of time).

Yes and we love them. They were a big selling point when we purchased the house having lived in a new build with windows that barely opened. We have them open most days and the cool breeze is lovely.

Thanks! So your experience is that they do create more breeze than a traditional window which opens only at the bottom? Do you find it made a difference during heatwaves or not so much?

My school had them, and they did make a noticeable difference. You could feel when someone opened both the top and bottom, as the air moved in the room.

I had these in my old house and I really miss them! They are so much better for air circulation on a hot day.

They are brilliant when it is hot. Create a lovely draft.

Yes they work. The downside with sash windows is that even when closed, they let in a hell of a lot of dust and grime from outside. Or at any rate the ones in our first house (Victorian terrace in S. London) did.

Yes, and it does work. Rarely need that much ventilation though.

As for draughts, old sash windows may need the beads repinned to reduce loose gaps. Probably best done during a general overhaul as they will need repainting afterwards.

The furry strips (sometimes called brush pile) are good for draughts, because they allow the sashes to slide without binding. The pile is soft and fine, somewhere between velvet and cats' fur.

I use the stuff on a metal backing strip, bought by the roll. There are various sizes. It needs to be fixed very securely at each end to prevent it being dislodged. It is quite hard to fix round the fitches.

Yes, they really do make a difference! Had them in my last house in the UK.

@PigletJohn but do PVC and aluminium windows insulate better and have less draught than a wooden sash window?

The wooden sash windows I have seen were terrible with insulation. I'm hoping better versions exist now.

They are never going to be as good at insulating as uPVC casement double glazed windows because of the mechanism that they use to work so it will always be a trade off. The new ventrolla systems which are the brush things mentioned by pigletjohn are good and make a huge difference to drafts.

However they can be if you also put secondary glazing in place but obviously this is a faff and needs removing in summer so you can open the windows.

As is often the case, you can't have everything yet.

uPVC sashes are less leaky than wooden ones but they are a nightmare to open and close because they are heavy and the spring systems are totally crap compared with the old weights.

Ask in Scotsnet - tenement flats are more likely to have these. I shared a flat when at uni in Scotland and the sash and case windows were fab, top and bottom open for circulation.

Then for insulation and cutting out noise at night, the flat still had the original foldaway shutters at the sides of the window. TheY blocked out light and noise and really helped as a first layer of insulation, curtains were then pulled to keep cosy. I've been in some homes where the shutters were halved horizontally so you could close top half or bottom half to reduce light or draughts during the day.

@PigletJohn "Rarely need that much ventilation though."

Not my experience.
The point is not how often it is very hot outside but how often it is very hot indoors.

It is rare for it to be 30C outdoors, but in some properties it is not rare for it to be 23c outdoors and 30c indoors. Especially in lofts, south facing rooms or overly insulated newbuilds.

We have new wooden sash windows with double glazing. We’re in a conservation area so had to have (expensive) wood. They are not draughty at all. Last summer wasn’t a good test of their ventilation powers here so I can’t really comment on that. I’ve never seen a sash window that didn’t open top and bottom, I don’t think it’s traditional to only open at the bottom.

Absolutely agree with this. Victorian terrace in W.London and the dust/grime/sludge!

@PigletJohn Long time no see!!